The research plan includes a continuation of seroepidemiologic investigations using ELISA to assess the prevalence and incidence of S. japonicum infection in the Philippines especially in children; such information is vital to the evaluation of the ongoing integrated control program. Current assessment dependent on stool examination will not yield reliable results. The serologic evaluation of the efficacy of Praziquantel therapy in children and adults will be completed. The plan also includes the development of variations of ELISA methodology to detect schistosome antigens in the blood and urine and in the differentiation of newly acquired from older infections. Once developed and proven reliable, these technics will be employed to expand the usefulness of ELISA in approaching other field problems such as the serolobic evaluation of intensity of infection and correlation with clinical gradients of disease. A quantitative stool examination for reference will underlie all these studies; clinical evaluations of patients will be made as warranted.